Packing of soil is of progressively greater problem in agricultural regions. In soils subject to packing, the repetition of work and use of heavy materials give rise to compact regions, truly barriers to the development of roots and the movement of water. It becomes necessary therefore these days to loosen soils by causing a decompaction and a division of the compact region so as thereby to reestablish the natural system of passages and discontinuities in the ground without substantially disturbing the surface. The decompacting devices must therefore nowadays effectively break up the beds by loosening the soil evenly over the width and the depth that is worked. The design of the blades is a determining factor to meet this problem. It has been known for 70 years that there has been a development of blades provided on the market. The decompacting blades for 70 years have been all characterized by a working portion, called a body, essentially vertical and a heel disposed at the level of the lower edge of the body in said vertical plane formed by the body. There results a certain number of drawbacks. Thus, high power is absorbed, strong lateral compression is caused and there is a smoothing behind the working area. Finally, the profile of the worked surface obtained was heterogeneous and the structure of the soil was overturned.
To overcome these drawbacks, it has been proposed to develop during the last 80 years, curved blades which have, relative to a vertical plane, an inclination at the level of the body, of about 45.degree., or even greater than 45.degree.. These blades were provided with wear members generally made in several parts and located in the forward or rear portion of the blade. Thus, there was provided at the rear of each blade a vane whose inclination was adjustable, this vane permitting more or less accentuating the raising and breaking up of the ground as a function of its nature and its moisture. These blades however had different drawbacks. They were in the first place entirely too complicated to produce, relatively fragile and difficult to maintain. Moreover, the surface aspects obtained by means of these blades was difficult to control. Thus, the raising action exerted by these blades was an oblique raising action connected to the great inclination of the body. From this great inclination resulted a so-called "cathedral" effect.
It thus seemed necessary to develop a blade not having the mentioned drawbacks, namely a blade permitting loosening the soil by a substantially vertical raising action giving rise to no smoothing effect of the ground and not overturning the layers of dirt.